Abstract Electromagnetic pulse welding (EMPW) is an environmentally-friendly, fast, and efficient welding technology for dissimilar metals. In this study, a 28 kJ/20 kV EMPW system is designed and developed to carry out the EMPW experiment of welding 1060 aluminum plate and T2 copper plate. The complete process of the jet has been captured during the welding process through an integrated observation system. And a micro-gap discharge is also first discovered during the transient physical process. The results of the scanning electron microscopy (SEM) and the energy dispersive spectrometry (EDS) analysis show that the interface morphologies of the ablation caused by the micro-gap discharge and the EMPW seam are different. A 3D finite element simulation model is established to investigate the cause of the micro-gap discharge in COMSOL Multiphysics. Based on the analysis of the motion behavior of the plate and the distribution of electromagnetic parameters, the simulation results show that the micro-gap discharge may be the result of the fact that the electric field strength is higher than the breakdown strength of air. Thus, the micro-gap discharge can release the energy of the plate. And the site where the micro-gap discharge is released is related to the induced potential difference and the contact pressure. This paper explains the formation of potholes on the welding surface, trying to enrich the study on the transient physical process of the EMPW.

中文翻译：

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Cu-Al板EMPW工艺中射流和微间隙放电的研究

摘要 电磁脉冲焊接（EMPW）是一种环保、快速、高效的异种金属焊接技术。本研究设计开发了28 kJ/20 kV EMPW系统，进行1060铝板与T2铜板焊接的EMPW实验。在焊接过程中，通过集成的观察系统捕获了射流的完整过程。并且在瞬态物理过程中也首次发现了微间隙放电。扫描电子显微镜（SEM）和能谱分析（EDS）结果表明，微间隙放电引起的烧蚀界面形貌与 EMPW 焊缝不同。建立 3D 有限元仿真模型以研究 COMSOL Multiphysics 中微间隙放电的原因。通过对极板运动行为和电磁参数分布的分析，仿真结果表明微间隙放电可能是电场强度高于空气击穿强度的结果。因此，微间隙放电可以释放极板的能量。而微间隙放电释放的部位与感应电位差和接触压力有关。本文解释了焊接表面坑洞的形成，试图丰富对电磁脉冲瞬态物理过程的研究。仿真结果表明，微间隙放电可能是电场强度高于空气击穿强度的结果。因此，微间隙放电可以释放极板的能量。而微间隙放电释放的部位与感应电位差和接触压力有关。本文解释了焊接表面坑洞的形成，试图丰富对电磁脉冲瞬态物理过程的研究。仿真结果表明，微间隙放电可能是电场强度高于空气击穿强度的结果。因此，微间隙放电可以释放极板的能量。而微间隙放电释放的部位与感应电位差和接触压力有关。本文解释了焊接表面坑洞的形成，试图丰富对电磁脉冲瞬态物理过程的研究。